Bridge interconnection with layered interconnect structures

ABSTRACT

Embodiments of the present disclosure are directed towards techniques and configurations for layered interconnect structures for bridge interconnection in integrated circuit assemblies. In one embodiment, an apparatus may include a substrate and a bridge embedded in the substrate. The bridge may be configured to route electrical signals between two dies. An interconnect structure, electrically coupled with the bridge, may include a via structure including a first conductive material, a barrier layer including a second conductive material disposed on the via structure, and a solderable material including a third conductive material disposed on the barrier layer. The first conductive material, the second conductive material, and the third conductive material may have different chemical composition. Other embodiments may be described and/or claimed.

FIELD

Embodiments of the present disclosure generally relate to the field ofintegrated circuits, and more particularly, to techniques andconfigurations for bridge interconnection with layered interconnectstructures, in integrated circuit assemblies.

BACKGROUND

Embedded bridge interconnection may provide faster communication betweenprocessors and memory chips. Various dies may need to be attached to asubstrate at the first level interconnection (FLI) to enable highperformance computing (HPC). As dies continue to shrink to smallerdimensions, a finer pitch is generally needed between interconnectstructures at the FLI level.

Providing a finer pitch for future computing devices may be challengingusing present technologies. For example, presently, a mixed bump pitchbetween processor die and memory die, may make packaging and assemblyvery challenging and result in poor yield performance. FLI jointarchitecture that employs a solder paste printing (SPP) process mayresult in yield failures due to limitations to solder bump height and/orsolder volume on the dies, which may result in non-contact opens andbump cracks, especially for smaller pitch areas of the FLI. Moreover,electromigration risk may be elevated due to copper (Cu) diffusion andorganic solder preservative (OSP) surface finish used on a substrateside for FLI joint.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be readily understood by the following detaileddescription in conjunction with the accompanying drawings. To facilitatethis description, like reference numerals designate like structuralelements. Embodiments are illustrated by way of example and not by wayof limitation in the figures of the accompanying drawings.

FIG. 1 schematically illustrates a cross-section side view of an exampleintegrated circuit (IC) assembly configured to use embedded bridgeinterconnections with layered interconnect structures in a substrate, inaccordance with some embodiments.

FIG. 2 schematically illustrates a flow diagram of a package substratefabrication process for forming a substrate embedded with bridgeinterconnection using layered interconnect structures, in accordancewith some embodiments.

FIG. 3 schematically illustrates cross-sectional views of some selectedoperations, prior to embedding a bridge in a substrate, in connectionwith the package substrate fabrication process illustrated in FIG. 2, inaccordance with some embodiments.

FIG. 4 schematically illustrates cross-sectional views of some otherselected operations, prior to embedding a bridge in a substrate, inconnection with the package substrate fabrication process illustrated inFIG. 2, in accordance with some embodiments.

FIG. 5 schematically illustrates cross-sectional views of some selectedoperations to embed a bridge in a substrate, in connection with thepackage substrate fabrication process illustrated in FIG. 2, inaccordance with some embodiments.

FIG. 6 schematically illustrates cross-sectional views of some selectedoperations to form a layered interconnect structure, in connection withthe package substrate fabrication process illustrated in FIG. 2, inaccordance with some embodiments.

FIG. 7 schematically illustrates cross-sectional views of some otherselected operations to form a layered interconnect structure, inconnection with the package substrate fabrication process illustrated inFIG. 2, in accordance with some embodiments.

FIG. 8 schematically illustrates cross-sectional views of some selectedoperations to finalize a layered interconnect structure, in connectionwith the package substrate fabrication process illustrated in FIG. 2, inaccordance with some embodiments.

FIG. 9 schematically illustrates a flow diagram of an assembly processutilizing a package substrate with embedded bridge interconnections, inaccordance with some embodiments.

FIG. 10 schematically illustrates a computing device that includesembedded bridge interconnections with layered interconnect structures ina substrate as described herein, in accordance with some embodiments.

DETAILED DESCRIPTION

Embodiments of the present disclosure describe techniques andconfigurations for bridge interconnection with layered interconnectstructures, in integrated circuit assemblies. In the followingdescription, various aspects of the illustrative implementations will bedescribed using terms commonly employed by those skilled in the art toconvey the substance of their work to others skilled in the art.However, it will be apparent to those skilled in the art thatembodiments of the present disclosure may be practiced with only some ofthe described aspects. For purposes of explanation, specific numbers,materials and configurations are set forth in order to provide athorough understanding of the illustrative implementations. However, itwill be apparent to one skilled in the art that embodiments of thepresent disclosure may be practiced without the specific details. Inother instances, well-known features are omitted or simplified in ordernot to obscure the illustrative implementations.

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, wherein like numeralsdesignate like parts throughout, and in which is shown by way ofillustration embodiments in which the subject matter of the presentdisclosure may be practiced. It is to be understood that otherembodiments may be utilized and structural or logical changes may bemade without departing from the scope of the present disclosure.Therefore, the following detailed description is not to be taken in alimiting sense, and the scope of embodiments is defined by the appendedclaims and their equivalents.

For the purposes of the present disclosure, the phrase “A and/or B”means (A), (B), or (A and B). For the purposes of the presentdisclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B),(A and C), (B and C), or (A, B and C).

The description may use perspective-based descriptions such astop/bottom, in/out, over/under, and the like. Such descriptions aremerely used to facilitate the discussion and are not intended torestrict the application of embodiments described herein to anyparticular orientation.

The description may use the phrases “in an embodiment”, “inembodiments”, or “in some embodiments” which may each refer to one ormore of the same or different embodiments. Furthermore, the terms“comprising,” “including,” “having,” and the like, as used with respectto embodiments of the present disclosure, are synonymous.

The term “coupled with” along with its derivatives, may be used herein.“Coupled” may mean one or more of the following. “Coupled” may mean thattwo or more elements are in direct physical or electrical contact.However, “coupled” may also mean that two or more elements indirectlycontact each other, but yet still cooperate or interact with each other,and may mean that one or more other elements are coupled or connectedbetween the elements that are said to be coupled with each other. Theterm “directly coupled” may mean that two or more elements are in directcontact.

In various embodiments, the phrase “a first feature formed, deposited,or otherwise disposed on a second feature” may mean that the firstfeature is formed, deposited, or disposed over the second feature, andat least a part of the first feature may be in direct contact (e.g.,direct physical and/or electrical contact) or indirect contact (e.g.,having one or more other features between the first feature and thesecond feature) with at least a part of the second feature.

As used herein, the term “module” may refer to, be part of, or includean Application Specific Integrated Circuit (ASIC), an electroniccircuit, a system-on-chip (SoC), a processor (shared, dedicated, orgroup) and/or memory (shared, dedicated, or group) that execute one ormore software or firmware programs, a combinational logic circuit,and/or other suitable components that provide the describedfunctionality.

FIG. 1 schematically illustrates a cross-section side view of an exampleIC assembly 100 configured to use embedded bridge interconnections withlayered interconnect structures in a substrate, in accordance with someembodiments. In embodiments, IC assembly 100 may include one or moredies, such as die 110 and die 120, electrically and/or physicallycoupled with package substrate 150, as can be seen. Package substrate150 may further be electrically coupled with circuit board 190, as canbe seen. As used herein, first level interconnect (FLI) may refer to theinterconnect between a die and a package substrate while second levelinterconnect (SLI) may refer to the interconnect between a package and acircuit board.

Die 110 or 120 may represent a discrete unit made from a semiconductormaterial using semiconductor fabrication techniques such as thin filmdeposition, lithography, etching and the like. In some embodiments, die110 or 120 may include, or be a part of a processor, memory, SoC orASIC. Die 110 and 120 can be attached to package substrate 150 accordingto a variety of suitable configurations including, a flip-chipconfiguration, as depicted, or other configurations such as, forexample, being embedded in package substrate 150. In the flip-chipconfiguration, die 110 or 120 may be attached to a surface (e.g., sideS1) of package substrate 150 using FLI structures such as interconnectstructures 130, 135, which are configured to electrically and/ormechanically couple the dies 110, 120 with the package substrate 150 androute electrical signals between one or more of the dies 110, 120 andother electrical components. In some embodiments, the electrical signalsmay include input/output (I/O) signals and/or power/ground associatedwith operation of the dies 110, 120.

The interconnect structure 130 may be electrically coupled with thebridge 140 to route the electrical signals between the dies 110, 120using the bridge 140. The interconnect structure 130 may, as discussedfurther below, substantially inhibit diffusion and mitigateelectromigration risks and provide higher and more compliant FLI jointand standoff height, which may improve assembly performance, reduceassembly yield loss, and enhance FLI reliability.

The interconnect structure 135 may be configured to route the electricalsignals between a die (e.g., die 110) and an electrical pathway 133 thatpasses through the package substrate 150 from a first side S1 to asecond side S2 that is opposite to the first side S1. For example, theinterconnect structure 135 may be coupled with other interconnectstructures (e.g., interconnect structure 137) such as, for example,trenches, vias, traces, or conductive layers and the like that areconfigured to route electrical signals of the die 110 between the firstside S1 and the second side S2 of the package substrate 150. Theinterconnect structure 135 may be part of the electrical pathway 133 insome embodiments.

The interconnect structure 137 is merely an example structure for thesake of discussion and may represent any of a variety of suitableinterconnect structures and/or layers. Similarly configured interconnectstructures 130 and 135 may couple the die 120 or other dies (not shown)with the package substrate 150. The package substrate 150 may includemore or fewer interconnect structures or layers than depicted. In someembodiments, an electrically insulative material such as, for example,molding compound or underfill material (not shown) may partiallyencapsulate a portion of dies 110 or 120, and/or interconnect structures130, 135.

In some embodiments, bridge 140 may be configured to electricallyconnect dies 110 and 120 with one another. In some embodiments, bridge140 may include interconnect structures (e.g., interconnect structure130) to serve as electrical routing features between the dies 110 and120. In some embodiments, a bridge may be disposed between some dies onpackage substrate 150 and not between other dies. In some embodiments, abridge may not be visible from a top view. Bridge 140 may be embedded ina cavity of package substrate 150 in some embodiments. Bridge 140 may bea high density routing structure that provides routes for electricalsignals. Bridge 140 may include a bridge substrate composed of glass ora semiconductor material, such as high resistivity silicon (Si) havingelectrical routing interconnect features formed thereon, to provide achip-to-chip connection between the dies 110 and 120. Bridge 140 may becomposed of other suitable materials in other embodiments. In someembodiments, the package substrate 150 may include multiple embeddedbridges to route electrical signals between multiple dies.

In some embodiments, package substrate 150 is an epoxy-based laminatesubstrate having a core and/or build-up layers such as, for example, anAjinomoto Build-up Film (ABF) substrate. Package substrate 150 mayinclude other suitable types of substrates in other embodimentsincluding, for example, substrates formed from glass, ceramic, orsemiconductor materials.

Circuit board 190 may be a printed circuit board (PCB) composed of anelectrically insulative material such as an epoxy laminate. For example,circuit board 190 may include electrically insulating layers composed ofmaterials such as, for example, polytetrafluoroethylene, phenolic cottonpaper materials such as Flame Retardant 4 (FR-4), FR-1, cotton paper andepoxy materials such as CEM-1 or CEM-3, or woven glass materials thatare laminated together using an epoxy resin prepreg material. Structuressuch as traces, trenches, vias may be formed through the electricallyinsulating layers to route the electrical signals of the die 110 or 120through circuit board 190. Circuit board 190 may be composed of othersuitable materials in other embodiments. In some embodiments, circuitboard 190 is a motherboard (e.g., motherboard 1002 of FIG. 10).

Package-level interconnects such as, for example, solder balls 170 orland-grid array (LGA) structures may be coupled to one or more lands(hereinafter “lands 160”) on package substrate 150 and one or more pads180 on circuit board 190 to form corresponding solder joints that areconfigured to further route the electrical signals between the packagesubstrate 150 and the circuit board 190. Lands 160 and/or pads 180 maybe composed of any suitable electrically conductive material such asmetal including, for example, nickel (Ni), palladium (Pd), gold (Au),silver (Ag), copper (Cu), and combinations thereof. Other suitabletechniques to physically and/or electrically couple package substrate150 with circuit board 190 may be used in other embodiments.

FIG. 2 schematically illustrates a flow diagram of a package substratefabrication process (hereinafter “process 200”) for forming a substrate(e.g., package substrate 150 of FIG. 1) embedded with bridgeinterconnection using layered interconnect structures (e.g.,interconnect structure 130 of FIG. 1), in accordance with someembodiments. The process 200 may comport with embodiments described inconnection with FIGS. 3-8 according to various embodiments.

At 210, the process 200 may include forming a bridge (e.g., bridge 140of FIG. 1) in a substrate. In embodiments, the bridge may be composed ofglass or a semiconductor material (e.g., Si) and include electricalrouting features to route electrical signals between dies. In someembodiments, the bridge may be disposed in or within a plane formed byone or more build-up layers of the substrate. For example, as can beseen in the depicted embodiment in connection with FIG. 1, bridge 140 isembedded in the build-up layers of substrate 150. In some embodiments,the bridge may be disposed in a plane formed by the build-up layers, butformed separately from the build-up layers.

In some embodiments, forming the bridge (e.g., bridge 140 of FIG. 1)disposed in a plane of the build-up layers may be performed by embeddingthe bridge in build-up layers as part of the formation of the build-uplayers or by forming a cavity in the build-up layers and placing thebridge in the cavity subsequent to formation of the build-up layers,according to any suitable technique. The bridge may be embedded in thesubstrate during fabrication described in connection with FIGS. 3-5according to various embodiments.

At 220, the process 200 may include forming a joint including a firstconductive material, connected with the bridge to route electricalsignals beyond a surface of the substrate. In embodiments, the joint maybe a part of the interconnect structure (e.g., interconnect structure130 of FIG. 1) that may electrically couple the bridge to a die. Thejoint may include the first electrically conductive material. In oneembodiment, the first electrically conductive material may include Cu.In other embodiments, the first electrically conductive material mayinclude other chemical compositions, or combinations thereof. Inembodiments, the joint may include structures such as, for example,traces, trenches, vias, lands, pads or other structures that providecorresponding electrical pathways for electrical signals of a diethrough the package substrate to an embedded bridge, then, for example,to another die electrically coupled to the bridge. In one embodiment,the joint may include a via structure. In an embodiment, the joint mayfurther include a pad structure coupled with the via structure. Thejoint may be formed during fabrication described in connection with FIG.6 according to various embodiments.

At 230, the process 200 may include forming a barrier layer including asecond conductive material, directly on the joint. In embodiments, thebarrier layer may include the second electrically conductive material,such as a barrier metal, and be applied to cover the joint. The barrierlayer may reduce or prevent diffusion of the first conductive materialused in the joint into surrounding materials, while maintaining anelectrical connection between the joint and a die. The second conductivematerial may have a different chemical composition than the firstconductive material. The second electrically conductive material mayinclude, for example, nickel (Ni), tantalum (Ta), hafnium (Hf), niobium(Nb), zirconium (Zr), vanadium (V), tungsten (W), or combinationsthereof. In some embodiments, the second electrically conductivematerial may include conductive ceramics, such as tantalum nitride,indium oxide, copper silicide, tungsten nitride, and titanium nitride.

In embodiments, the barrier layer may mitigate the risk ofelectromigration. The risk of electromigration may increase with higherdirect current densities when structure size in electronics such asintegrated circuits (ICs) decreases. Electromigration may causediffusion processes, such as grain boundary diffusion, bulk diffusion,or surface diffusion. In embodiments, when the first conductive materialincludes copper, surface diffusion may be dominant in copperinterconnects caused by electromigration. The barrier layer may preventcopper diffusion between the neighboring copper and/or copper alloylines. In one embodiment, electrolytic plating may be used to form thebarrier layer. The barrier layer may be formed during fabricationdescribed in connection with FIG. 7 according to various embodiments.

At 240, the process 200 may include forming a solder layer including athird conductive material, directly on the barrier layer, the barrierlayer and the solder layer being configured to route electrical signals.In embodiments, the solder layer may include a third electricallyconductive material, such as a fusible metal alloy, that is applied onthe barrier layer. The solder layer may be used to join together theunderlying structure including the barrier layer and the joint with adie via its connection points, while maintaining an electricalconnection between the underlying structure and the die. In embodiments,the joint, the barrier layer, and the solder layer may collectively forman interconnect structure to route electrical signals between the bridgeand a die.

In embodiments, the third conductive material may have a differentchemical composition than the first and second conductive material. Thethird electrically conductive material may include, for example, tin(Sn), silver (Ag), nickel (Ni), zinc (Zn), or combinations thereof. Thesolder layer may be formed during fabrication described in connectionwith FIG. 7 according to various embodiments. In other embodiments, thesolder layer may be formed by electrolytic plating, past printing, uballbumping, or other compatible processes.

Various operations are described as multiple discrete operations inturn, in a manner that is most helpful in understanding the claimedsubject matter. However, the order of description should not beconstrued as to imply that these operations are necessarily orderdependent. Operations of the process 200 may be performed in anothersuitable order than depicted. In some embodiments, the process 200 mayinclude actions described in connection with FIGS. 3-8 and vice versa.

FIG. 3 schematically illustrate cross-sectional views of some selectedoperations, prior to embedding a bridge, in connection with the packagesubstrate fabrication process 200 illustrated in FIG. 2, in accordancewith some embodiments. Referring to operation 392, the substrate isdepicted subsequent to forming a dielectric layer 320 over a patternedmetal layer 310, as can be seen. In embodiments, the patterned metallayer and any number of layers below the patterned metal layer may bepart of the substrate, and may be formed in any manner known in the art.For example, the patterned metal layer may be a top or outermostconductive layer of a build-up layer formed with a semi-additive process(SAP).

In embodiments, dielectric layer 320 may be composed of any of a widevariety of suitable dielectric materials including, for example,epoxy-based laminate material, silicon oxide (e.g., SiO₂), siliconcarbide (SiC), silicon carbonitride (SiCN), or silicon nitride (e.g.,SiN, Si₃N₄, etc.). Other suitable dielectric materials may also be usedincluding, for example, low-k dielectric materials having a dielectricconstant k that is smaller than a dielectric constant k of silicondioxide. In embodiments, dielectric layer 320 may be formed bydepositing a dielectric material using any suitable technique including,for example, atomic layer deposition (ALD), physical vapor deposition(PVD) or chemical vapor deposition (CVD) techniques. In embodiments,dielectric layer 320 may include a polymer (epoxy based resin) withsilica filler to provide suitable mechanical properties that meetreliability requirements of the package. In embodiments, dielectriclayer 320 may be formed as a film of polymer, such as by ABF lamination.Dielectric layer 320 may have a suitable ablation rate to enable laserpatterning as described elsewhere herein.

Referring to operation 394, the substrate is depicted subsequent toforming cavity 332 on dielectric layer 320, as can be seen. Inembodiments, cavity 332 may be a via hole which may be laser drilledinto dielectric layer 320 to expose a portion of the patterned metallayer 310. Any conventional technique may be used, such as employing CO2laser, to form cavity 332. In embodiments, a desmear process may besubsequently applied to remove smeared dielectric material, such asepoxy-resin, from the surface of the patterned metal layer 310, toprevent the smear residue to form another dielectric layer.

In embodiments, metallic seed layer 330 is then deposited on the top ofthe N−2 layer with any suitable techniques. In some embodiments,electroless plating may be used to form metallic seed layer 330. Forexample, a catalyst, such as palladium (Pd) may be deposited followed byan electroless copper (Cu) plating process. In some embodiments, aphysical vapor deposition (i.e., sputtering) technique may be used todeposit metallic seed layer 330. Referring to operation 396, thesubstrate is depicted subsequent to forming a photosensitive layer suchas, for example, a dry film resist (DFR) layer 336, as can be seen. Inembodiments, DFR layer 336 may be laminated and patterned using anytechnique known in the art. In embodiments, opening 328 in DFR layer 336may have bigger lateral dimensions than cavity 332, as can be seen.

FIG. 4 schematically illustrates cross-sectional views of some otherselected operations, prior to embedding a bridge, in connection with thepackage substrate fabrication process illustrated in FIG. 2, inaccordance with some embodiments. Referring to operation 492, thesubstrate is depicted subsequent to depositing a conductive materialinto cavity 332 and opening 328, as can be seen. In embodiments, theconductive material may include the first electrically conductivematerial, as discussed above, such as metal including, for example,nickel (Ni), palladium (Pd), gold (Au), silver (Ag), copper (Cu), andcombinations thereof. In embodiments, cavity 332 and opening 328 may befilled, for example, with an electrolytic plating process. Inembodiments, an electrolytic copper plating process may be performed tofill cavity 332 and opening 328. In embodiments, interconnect structure410 formed in operation 492 may protrude above the surface of the N−2layer.

Referring to operation 494, the substrate is depicted subsequent tostripping DFR, as can be seen. In embodiments, the DFR may be removedusing any conventional strip process. Referring to operation 496, thesubstrate is depicted subsequent to etching metallic seed layer 330, ascan be seen. In embodiments, DFR stripping may further delineateinterconnect structure 410 and expose the underlying dielectric layer320.

FIG. 5 schematically illustrates cross-sectional views of some selectedoperations to embed a bridge, in connection with the package substratefabrication process illustrated in FIG. 2, in accordance with someembodiments. Referring to operation 592, the substrate is depictedsubsequent to forming bridge cavity 502, as can be seen. In embodiments,bridge cavity 502 may be provided for placement of a bridge. Inembodiments, at least a part of dielectric layer 320 may be removed byexposure to heat or chemicals to form bridge cavity 502. In embodiments,bridge cavity 502 may be laser drilled into dielectric layer 320 toexpose a portion of the patterned metal layer 310. In other embodiments,bridge cavity 502 may be left open during fabrication of the previouslydiscussed build-up layers. In yet other embodiments, bridge cavity 502may be formed through the previously discussed build-up layers using apatterning process. For example, dielectric layer 320 may be composed ofa photosensitive material that is amenable to masking, patterning andetching, or develop processes.

Referring to operation 594, the substrate is depicted subsequent tomounting bridge 530 (only showing a part of the bridge), as can be seen.In embodiments, bridge 530 may include a bridge substrate composed ofglass or a semiconductor material, such as high resistivity silicon (Si)having electrical routing interconnect features formed thereon, toprovide a chip-to-chip connection between dies. In embodiments, bridge530 may be mounted on the patterned metal layer 310 using adhesive layer520. The material of adhesive layer 520 may include any suitableadhesive configured to withstand processes associated with fabricationof the substrate. In embodiments, chemical treatments, such as copperroughing technique, may be applied to improve adhesion between bridge530 and its surrounding surfaces. In embodiments, bridge 530 may haverouting features 540, such as pads, protruding above the surface of thebridge substrate, and configured as connection points to routeelectrical signals to and from bridge 530.

Referring to operation 596, the substrate is depicted subsequent toforming dielectric layer 550 over bridge 530, thus substantially formingthe N−1 layer on the N−2 Layer, as can be seen. In embodiments,dielectric layer 550 may be composed of any of a wide variety ofsuitable dielectric materials. In embodiments, dielectric layer 550 maybe formed by depositing a dielectric material using any suitabletechnique including, for example, atomic layer deposition (ALD),physical vapor deposition (PVD) or chemical vapor deposition (CVD)techniques. In embodiments, dielectric layer 320 may include a polymer(e.g., epoxy-based resin) and may further include a filler (e.g.,silica) to provide suitable mechanical properties that meet reliabilityrequirements of the package. In embodiments, dielectric layer 320 may beformed as a film of polymer, such as by ABF lamination. Dielectric layer550 may have a suitable ablation rate to enable laser patterning asdescribed elsewhere herein,

FIG. 6 schematically illustrates cross-sectional views of some selectedoperations to form a layered interconnect structure (e.g., interconnectstructure 130 of FIG. 1), in connection with the package substratefabrication process illustrated in FIG. 2, in accordance with someembodiments.

Referring to operation 692, the substrate is depicted subsequent toforming cavities 604 on dielectric layer 550, as can be seen. Inembodiments, a cavity may be a via hole which may be laser drilled intodielectric layer 550 to expose a portion of the underlying routingfeatures 540. Any conventional technique may be used, such as employingCO2 laser, to form cavities 604. In embodiments, a desmear process maybe subsequently applied to remove smeared dielectric material, such asepoxy-resin, from the bottom surface of cavity 604, to prevent the smearresidue to form another dielectric layer. In embodiments, metallic seedlayer 610 is then deposited on the top of the N−1 layer with anysuitable techniques. In some embodiments, electroless plating may beused to form metallic seed layer 610. For example, a catalyst, such aspalladium (Pd) may be deposited followed by an electroless copper (Cu)plating process. In some embodiments, a physical vapor deposition (i.e.,sputtering) technique may be used to deposit metallic seed layer 330.

Referring to operation 694, the substrate is depicted subsequent toforming a photosensitive layer such as, for example, dry film resist(DFR) layer 612, thus substantially forming the N layer on the N−1Layer, as can be seen. In embodiments, DFR layer 612 is laminated andpatterned using any technique known in the art. In embodiments, opening614 in DFR layer 612 may have bigger lateral dimensions than cavity 604.In embodiments, operation 694 may be performed on both the top andbottom side (e.g., side S1 and S2 of FIG. 1) of the substrate.

Referring to operation 696, the substrate is depicted subsequent todepositing a conductive material into cavity 604 and opening 614, as canbe seen. In embodiments, the conductive material may include the firstelectrically conductive material, as discussed above, such as metalincluding, for example, nickel (Ni), palladium (Pd), gold (Au), silver(Ag), copper (Cu), and combinations thereof. In embodiments, cavity 604and the opening 614 may be filled, for example, with an electrolyticplating process. In embodiments, an electrolytic copper plating processmay be performed to fill cavity 604 and opening 614 to form joint 620.At operation 696, over plated fill metal may be removed by one or moreof, etching, buff grinding, chemical-mechanical polishing, etc. toplanarize joint 620. For example, chemical, mechanical polishing (CMP)or buff grinding may be used to first planarize joint 620 and thenetching may be employed to remove any remaining fill metal from the topsurface of DFR layer 612. In embodiments, the interconnect structure orjoint 620 formed in operation 696 may protrude above the surface of theN−1 layer (e.g., in the formation of a pad structure) and be configuredto couple bridge 530 with dies.

In embodiments, other layered FLI interconnect structures (e.g.,interconnect structure 135 of FIG. 1) may be formed in part by theoperations of 692, 694, and 696.

FIG. 7 schematically illustrates cross-sectional views of some otherselected operations to form the layered interconnect structure, inconnection with the package substrate fabrication process illustrated inFIG. 2, in accordance with some embodiments. Referring to operation 792,the substrate is depicted subsequent to forming barrier layer 710directly on the joint, as can be seen. In embodiments, barrier layer 710may include the second electrically conductive material, such as abarrier metal, and be applied to cover the joint. Barrier layer 710 maybe configured to inhibit diffusion of the first conductive material usedin the joint, while maintaining an electrical connection between thejoint and a die. The second conductive material may differ with thefirst conductive material. The second electrically conductive materialmay include, for example, nickel (Ni), tantalum (Ta), tantalum nitride(TaN), titanium nitride (TiN), titanium tungsten (TiW), hafnium (Hf),niobium (Nb), zirconium (Zr), vanadium (V), or tungsten (W) andcombinations thereof. In some embodiments, the second electricallyconductive material may include conductive ceramics, such as tantalumnitride, indium oxide, copper silicide, tungsten nitride, and titaniumnitride. Barrier layer 710 may be composed of multiple layers ofdifferent materials in some embodiments. In embodiments, operation 792may include application of a protective film on the back side of thesubstrate.

Barrier layer 710 may be deposited using any suitable depositiontechnique. In some embodiments, one or more barrier materials of barrierlayer 710 may be deposited using PVD technique. Barrier layer 710 may beformed using other suitable deposition techniques in other embodiments.

Referring to operation 794, the substrate is depicted subsequent toforming solder layer 720 directly on the barrier layer, as can be seen.In embodiments, solder layer 720 may include the third electricallyconductive material, such as a fusible metal alloy, and be applied onbarrier layer 710. In embodiments, the third conductive material maydiffer with the first and second conductive material. The thirdelectrically conductive material may include, for example, tin (Sn),silver (Ag), nickel (Ni), zinc (Zn), and combinations thereof. Inembodiments, solder layer 720 may be used to join together theunderlying structure with a die and maintain an electrical connectionbetween the underlying structure and the die. In embodiments, joint 620,barrier layer 710, and solder layer 720 may collectively form aninterconnect structure to route electrical signals between bridge 530and one or more dies, such as die 110 and 120 in connection with FIG. 1.

Referring to operation 796, the substrate is depicted subsequent tostripping DFR layer 612, as can be seen. In embodiments, DFR layer 612may be removed using any conventional strip process. In embodiments,portions of metallic seed layer 610 may be removed, for example, byetching, so as to further delineate the interconnect structure. In someembodiments, the etch processes may include wet etching of metallic seedlayer 610. Other suitable etch techniques or chemistries may be used inother embodiments. In embodiments, the protective film on the back sideof the substrate may also be removed.

In embodiments, other layered FLI interconnect structures (e.g.,interconnect structure 135 of FIG. 1) may be partially formed by theoperations of 792, 794, and 796.

FIG. 8 schematically illustrates cross-sectional views of some selectedoperations to finalize a layered interconnect structure, in connectionwith the package substrate fabrication process illustrated in FIG. 2, inaccordance with some embodiments. Referring to operation 892, thesubstrate is depicted subsequent to exposing bump areas on a top side(e.g., side S1 of FIG. 1). In embodiments, a solder resist (SR) layermay be deposited on the dielectric layer 550. In embodiments, the SRlayer may be patterned at non-bump area to cover traces or otherelectrical routing features, also form fiducial pad for assembly, forexample pad 802. Subsequently, the bump area SR layer may be removed ona top side (e.g., side S1 of FIG. 1) of the substrate with techniquessuch as SR exposure or SR development. In other embodiments, the SRlayer may be removed from the bump area using any suitable techniqueincluding, for example, patterning techniques such as etch and/orlithography. In embodiments, operation 892 may additionally include SRlamination and formation of solder resist openings (SROs) on the bottom(e.g., side S2 of FIG. 1) of the substrate (not shown).

Referring to operation 894, the substrate is depicted subsequent toforming protective film 804, as can be seen. The protective film 804 mayprotect components on the top (e.g., side S1 of FIG. 1) of the substrateduring processing on the back (e.g., side S2 of FIG. 1) of thesubstrate. In embodiments, protective film 804 may be formed by anysuitable technique, such as thin film deposition technique. Inembodiments, a Nickel-Palladium-Gold (NiPdAu) lead surface finish (SF)may be applied on the back side of the substrate (not shown) while theprotective film 804 is applied to the top of the substrate.

Referring to operation 896, the substrate is depicted subsequent toforming a round bump top on the interconnect structure, as can be seen.In embodiments, protective film 804 may be removed first, and thensolder layer 720 may be reflowed into a round shape using a thermalprocess to elevate a temperature of the solder layer above a reflowtemperature of the solder material.

In embodiments, other layered FLI interconnect structures (e.g.,interconnect structure 135 of FIG. 1) may be partially formed by theoperations of 892, 894, and 896.

FIG. 9 schematically illustrates a flow diagram of an assembly process900 utilizing a package substrate with embedded bridge interconnections,in accordance with some embodiments. Such a package substrate may beproduced through the illustrative processes described in reference toFIGS. 2-8 above.

Assembly process 900 begins at operation 910 with receiving a packagesubstrate having an embedded bridge with layered interconnect structures(e.g., interconnect structure 130 of FIG. 1). The package substratedepicted in FIG. 8 may be used in the assembly process 900.

At operation 920, an IC chip may be received with chip I/O connectionpoints (e.g., pads, bumps or pillars). While the IC chip may generallybe of any conventional type, in some embodiments, the IC chip may be aprocessor, such as a microprocessor, having a large I/O count. In someembodiments the IC chip may be a memory die, having a large I/O count.In some embodiments, solder may be applied to the chip I/O connectionpoints.

At operation 930, the IC chip may be aligned with the package substratesuch that the soldered chip I/O connection points are aligned with thelayered interconnect structures. Solderable material of the layeredinterconnect structures and/or solder on the chip I/O connection pointsis then reflowed at operation 940 to affix the IC chip to the layeredinterconnect structures. Additional operations may be performed tocomplete the packaging at 950. For example, in some embodiments, anelectrically insulative material may be deposited to encapsulate orpartially encapsulate the IC chip and/or the package substrate may befurther coupled with a circuit board.

Embodiments of the present disclosure may be implemented into a systemusing any suitable hardware and/or software to configure as desired.FIG. 10 schematically illustrates a computing device that includesembedded bridge interconnections with layered interconnect structures ina substrate as described herein, in accordance with some embodiments.The computing device 1000 may house a board such as motherboard 1002.Motherboard 1002 may include a number of components, including but notlimited to processor 1004 and at least one communication chip 1006.Processor 1004 may be physically and electrically coupled to motherboard1002. In some implementations, the at least one communication chip 1006may also be physically and electrically coupled to motherboard 1002. Infurther implementations, communication chip 1006 may be part ofprocessor 1004.

Depending on its applications, computing device 1000 may include othercomponents that may or may not be physically and electrically coupled tomotherboard 1002. These other components may include, but are notlimited to, volatile memory (e.g., DRAM), non-volatile memory (e.g.,ROM), flash memory, a graphics processor, a digital signal processor, acrypto processor, a chipset, an antenna, a display, a touchscreendisplay, a touchscreen controller, a battery, an audio codec, a videocodec, a power amplifier, a global positioning system (GPS) device, acompass, a Geiger counter, an accelerometer, a gyroscope, a speaker, acamera, and a mass storage device (such as hard disk drive, compact disk(CD), digital versatile disk (DVD), and so forth).

Communication chip 1006 may enable wireless communications for thetransfer of data to and from computing device 1000. The term “wireless”and its derivatives may be used to describe circuits, devices, systems,methods, techniques, communications channels, etc., that may communicatedata through the use of modulated electromagnetic radiation through anon-solid medium. The term does not imply that the associated devices donot contain any wires, although in some embodiments they might not.Communication chip 1006 may implement any of a number of wirelessstandards or protocols, including but not limited to Institute forElectrical and Electronic Engineers (IEEE) standards including Wi-Fi(IEEE 802.11 family), IEEE 802.16 standards (e.g., IEEE 802.16-2005Amendment), Long-Term Evolution (LTE) project along with any amendments,updates, and/or revisions (e.g., advanced LTE project, ultra mobilebroadband (UMB) project (also referred to as “3GPP2”), etc.). IEEE802.16 compatible BWA networks are generally referred to as WiMAXnetworks, an acronym that stands for Worldwide Interoperability forMicrowave Access, which is a certification mark for products that passconformity and interoperability tests for the IEEE 802.16 standards.Communication chip 1006 may operate in accordance with a Global Systemfor Mobile Communication (GSM), General Packet Radio Service (GPRS),Universal Mobile Telecommunications System (UMTS), High Speed PacketAccess (HSPA), Evolved HSPA (E-HSPA), or LTE network. Communication chip1006 may operate in accordance with Enhanced Data for GSM Evolution(EDGE), GSM EDGE Radio Access Network (GERAN), Universal TerrestrialRadio Access Network (UTRAN), or Evolved UTRAN (E-UTRAN). Communicationchip 1006 may operate in accordance with Code Division Multiple Access(CDMA), Time Division Multiple Access (TDMA), Digital Enhanced CordlessTelecommunications (DECT), Evolution-Data Optimized (EV-DO), derivativesthereof, as well as any other wireless protocols that are designated as3G, 4G, 5G, and beyond. Communication chip 1006 may operate inaccordance with other wireless protocols in other embodiments.

Computing device 1000 may include a plurality of communication chips1006. For instance, a first communication chip 1006 may be dedicated toshorter range wireless communications such as Wi-Fi and Bluetooth, and asecond communication chip 1006 may be dedicated to longer range wirelesscommunications such as GPS, EDGE, GPRS, COMA, WiMAX, LTE, Ev-DO, andothers.

Processor 1004 of computing device 1000 may be packaged in an ICassembly (e.g., IC assembly 100 of FIG. 1) that includes a substrate(e.g. package substrate 150 of FIG. 1) having embedded bridges withlayered interconnect structures as described herein. For example,circuit board 190 of FIG. 1 may be motherboard 1002, and processor 1004may be die 110 coupled to package substrate 150 using interconnectstructure 130 of FIG. 1. Package substrate 150 and motherboard 1002 maybe coupled together using package level interconnects. The term“processor” may refer to any device or portion of a device thatprocesses electronic data from registers and/or memory to transform thatelectronic data into other electronic data that may be stored inregisters and/or memory.

Communication chip 1006 may also include a the (e.g., the 120 of FIG. 1)that may be packaged in an IC assembly (e.g., IC assembly 100 of FIG. 1)that includes a substrate (e.g. package substrate 150 of FIG. 1) havingembedded bridges with layered interconnect structures as describedherein. In further implementations, another component (e.g., memorydevice or other integrated circuit device) housed within computingdevice 1000 may include a die (e.g., die 110 of FIG. 1) that may bepackaged in an IC assembly (e.g., IC assembly 100 of FIG. 1) thatincludes a substrate (e.g. package substrate 150 of FIG. 1) havingembedded bridges with layered interconnect structures as describedherein. According to some embodiments, multiple processor chips and/ormemory chips may be disposed on a same package substrate and theembedded bridges with layered interconnect structures may electricallyroute signals between any two of the processor or memory chips. In someembodiments, a single processor chip may be coupled with anotherprocessor chip using a first embedded bridge and a memory chip using asecond embedded bridge.

In various implementations, computing device 1000 may be a laptop, anetbook, a notebook, an Ultrabook™, a smartphone, a tablet, a personaldigital assistant (PDA), an ultra mobile PC, a mobile phone, a desktopcomputer, a server, a printer, a scanner, a monitor, a set-top box, anentertainment control unit, a digital camera, a portable music player,or a digital video recorder. In further implementations, the computingdevice 1000 may be any other electronic device that processes data.

Examples

According to various embodiments, the present disclosure describes anapparatus or integrated circuit assembly which may include a substrate,a bridge embedded in the substrate, the bridge being configured to routeelectrical signals between a first die and a second die; and aninterconnect structure electrically coupled with the bridge. Theinterconnect structure may include a via structure including a firstconductive material, the via structure being disposed to route theelectrical signals through at least a portion of the substrate, abarrier layer including a second conductive material disposed on the viastructure, and a solderable material including a third conductivematerial disposed on the barrier layer. The first conductive material,the second conductive material, and the third conductive material mayhave different chemical composition.

In embodiments, the bridge may further include a pad. The firstconductive material may be in direct contact with the pad.

In embodiments, the via structure may protrude beyond a surface of anoutermost build-up layer of the substrate.

In embodiments, the barrier layer may cover a surface of the viastructure to inhibit diffusion of the first conductive material throughthe barrier layer.

In embodiments, the first die may include a processor, and the seconddie may include a memory die or another processor.

In embodiments, the electrical signals may be input/output (I/O)signals.

In embodiments, the bridge may include a semiconductor materialincluding silicon (Si), and the substrate may include an epoxy-baseddielectric material.

In embodiments, the bridge may be embedded in the substrate using ABFlamination.

In embodiments, the first conductive material may include copper (Cu);the second conductive material may include nickel (Ni); and the thirdconductive material may include tin (Sn).

According to various embodiments, the present disclosure describes offabricating a packing substrate of an integrated circuit assembly. Insome embodiments, the method includes embedding a bridge in a substrate,forming a joint including a first conductive material, connected withthe bridge to route electrical signals beyond a surface of thesubstrate; forming a barrier layer including a second conductivematerial, directly on the joint; and forming a solder layer including athird conductive material, directly on the barrier layer. The barrierlayer and the solder layer may be configured to route the electricalsignals.

In embodiments, embedding the bridge in the substrate may furtherinclude forming a bridge cavity, placing the bridge in the bridgecavity, and laminating a dielectric material over the bridge.

In embodiments, forming the joint may further include forming a viacavity in the substrate, forming an opening in a photosensitive materialover the via cavity, and depositing the first conductive material intothe via cavity and the opening using a plating process.

In embodiments, forming the barrier layer may include depositing thesecond conductive material on the joint.

In embodiments, forming the solder layer may include depositing thethird conductive material on the barrier layer.

In embodiments, the method may further include reflowing the solderlayer to form a round bump.

In embodiments, the first conductive material may include copper (Cu);the second conductive material may include nickel (Ni); and the thirdconductive material may include tin (Sn).

According to various embodiments, the present disclosure describes astorage medium, having multiple instructions configured to cause adevice, in response to execution of the instructions by the device, topractice any previously described method.

According to various embodiments, the present disclosure describes anapparatus for bridge interconnection having means to practice anypreviously described method.

According to various embodiments, the present disclosure describes aproduct fabricated by any previously described method.

According to various embodiments, the present disclosure describes asystem or computing device including a first die and a second die; and asubstrate with an embedded bridge and an interconnect structure. Thebridge and the interconnect structure may be configured to routeelectrical signals between the first die and the second die.

The interconnect structure may include a via structure including a firstconductive material, the via structure being disposed to route theelectrical signals through at least a portion of the substrate, abarrier layer including a second conductive material disposed on the viastructure, and a solderable material including a third conductivematerial disposed on the barrier layer. The first conductive material,the second conductive material, and the third conductive material mayhave different chemical composition.

In embodiments, the first conductive material may include copper (Cu);the second conductive material may include nickel (Ni); and the thirdconductive material may include tin (Sn).

In embodiments, the bridge may include a semiconductor material, thesemiconductor material including silicon (Si). The substrate may includea dielectric material.

In embodiments, the first die may include a processor, and the seconddie may include a memory die or another processor.

In embodiments, the first die may include a memory die, and the seconddie may include another memory die or a processor.

In some embodiments, the system or computing device may further includea circuit board. The circuit board may be configured to route theelectrical signals of the die and one or more of an antenna, a display,a touchscreen display, a touchscreen controller, a battery, an audiocodec, a video codec, a power amplifier, a global positioning system(GPS) device, a compass, a Geiger counter, an accelerometer, agyroscope, a speaker, or a camera coupled with the circuit board. Insome embodiments, the system or computing device is one of a wearablecomputer, a smartphone, a tablet, a personal digital assistant, a mobilephone, an ultra mobile PC, an Ultrabook™, a netbook, a notebook, alaptop, a desktop computer, a server, a printer, a scanner, a monitor, aset-top box, an entertainment control unit, a digital camera, a portablemusic player, or a digital video recorder.

Various embodiments may include any suitable combination of theabove-described embodiments including alternative (or) embodiments ofembodiments that are described in conjunctive form (and) above (e.g.,the “and” may be “and/or”). Furthermore, some embodiments may includeone or more articles of manufacture (e.g., non-transitorycomputer-readable media) having instructions, stored thereon, that whenexecuted result in actions of any of the above-described embodiments.Moreover, some embodiments may include apparatuses or systems having anysuitable means for carrying out the various operations of theabove-described embodiments.

The above description of illustrated implementations, including what isdescribed in the Abstract, is not intended to be exhaustive or to limitthe embodiments of the present disclosure to the precise formsdisclosed. While specific implementations and examples are describedherein for illustrative purposes, various equivalent modifications arepossible within the scope of the present disclosure, as those skilled inthe relevant art will recognize.

These modifications may be made to embodiments of the present disclosurein light of the above detailed description. The terms used in thefollowing claims should not be construed to limit various embodiments ofthe present disclosure to the specific implementations disclosed in thespecification and the claims. Rather, the scope is to be determinedentirely by the following claims, which are to be construed inaccordance with established doctrines of claim interpretation.

What is claimed is:
 1. An apparatus comprising: a substrate; a bridgeembedded in the substrate, the bridge being configured to routeelectrical signals between a first die and a second die; and aninterconnect structure electrically coupled with the bridge, theinterconnect structure including: a via structure including a firstconductive material, the via structure being disposed to route theelectrical signals through at least a portion of the substrate, abarrier layer including a second conductive material disposed on the viastructure, and a solderable material including a third conductivematerial disposed on the barrier layer, wherein the first conductivematerial, the second conductive material and the third conductivematerial have different chemical composition.
 2. The apparatus of claim1, wherein: the bridge includes a pad; and the first conductive materialis in direct contact with the pad.
 3. The apparatus of claim 1, whereinthe via structure protrudes beyond a surface of an outermost build-uplayer of the substrate.
 4. The apparatus of claim 1, wherein the barrierlayer covers a surface of the via structure to inhibit diffusion of thefirst conductive material.
 5. The apparatus of claim 1, wherein thefirst die includes a processor and the second die includes a memory dieor another processor.
 6. The apparatus of claim 1, wherein theelectrical signals are input/output (I/O) signals.
 7. The apparatus ofclaim 1, wherein the bridge comprises a semiconductor material includingsilicon (Si), and wherein the substrate comprises an epoxy-baseddielectric material.
 8. The apparatus of claim 1, wherein the bridge isembedded in the substrate using Ajinomoto Build-up Film (ABF)lamination.
 9. The apparatus of claim 1, wherein first conductivematerial comprises copper (Cu), the second conductive material comprisesnickel (Ni), and the third conductive material comprises tin (Sn).
 10. Amethod comprising: embedding a bridge in a substrate; forming a jointincluding a first conductive material, connected with the bridge toroute electrical signals beyond a surface of the substrate; forming abarrier layer including a second conductive material, directly on thejoint; and forming a solder layer including a third conductive material,directly on the barrier layer, the barrier layer and the solder layerbeing configured to route the electrical signals.
 11. The method ofclaim 10, wherein embedding the bridge in the substrate comprises:forming a bridge cavity; placing the bridge in the bridge cavity; andlaminating a dielectric material over the bridge.
 12. The method ofclaim 10, wherein forming the joint comprises: forming a via cavity inthe substrate; forming an opening in a photosensitive material over thevia cavity; and depositing the first conductive material into the viacavity and the opening using a plating process.
 13. The method of claim10, wherein forming the barrier layer comprises: depositing the secondconductive material on the joint.
 14. The method of claim 10, whereinforming the solder layer comprises: depositing the third conductivematerial on the barrier layer.
 15. The method of claim 10, furthercomprising: reflowing the solder layer to form a round bump.
 16. Themethod of claim 10, wherein first conductive material comprises copper(Cu), the second conductive material comprises nickel (Ni), and thethird conductive material comprises tin (Sn).
 17. A system comprising: afirst die and a second die; and a substrate with an embedded bridge andan interconnect structure; the bridge and the interconnect structurebeing configured to route electrical signals between the first die andthe second die; the interconnect structure electrically coupled with thebridge, the interconnect structure including: a via structure includinga first conductive material, the via structure being disposed to routethe electrical signals through at least a portion of the substrate, abarrier layer including a second conductive material disposed on the viastructure, and a solderable material including a third conductivematerial disposed on the barrier layer, wherein the first conductivematerial, the second conductive material and the third conductivematerial have different chemical composition.
 18. The system of claim17, wherein the bridge comprises a semiconductor material, thesemiconductor material including silicon (Si).
 19. The system of claim17, wherein the barrier layer covers a surface of the via structure toinhibit diffusion of the first conductive material.
 20. The system ofclaim 17, wherein the first die includes a processor and the second dieincludes a memory die or another processor.
 21. The system of claim 17,wherein first conductive material comprises copper (Cu), the secondconductive material comprises nickel (Ni), and the third conductivematerial comprises tin (Sn).
 22. The system of claim 17, furthercomprising: a circuit board, wherein the substrate is electricallycoupled with the circuit board and the circuit board is configured toroute the electrical signals of the first die or the second die; and oneor more of an antenna, a display, a touchscreen display, a touchscreencontroller, a battery, an audio codec, a video codec, a power amplifier,a global positioning system device, a compass, a Geiger counter, anaccelerometer, a gyroscope, a speaker, or a camera coupled with thecircuit board.
 23. The system of claim 17, wherein the system is one ofa wearable computer, a smartphone, a tablet, a personal digitalassistant, a mobile phone, an ultra mobile PC, an ultrabook, a netbook,a notebook, a laptop, a desktop computer, a server, a printer, ascanner, a monitor, a set-top box, an entertainment control unit, adigital camera, a portable music player, or a digital video recorder.